Composer.json

Hi,

I know the commits seem messy (and they are), but I finally added a working composer.json to your project, so that it's able to be used with Composer. I also added a link to packagist.org. Feel free to merge my changes and just give me a short note – I'll then update the URL for that package.

Last but not least: It would be good to tag the current version to "1.0" after the merge is done. Thus makes it more safe for future updates of the master branch.

https://packagist.org/packages/tylerhall/smushit-php

Cheers from Berlin, Germany,
Marco